Novel glue product for gluing veneers and cross-ply sheets



Patented Dec.28,'1937- v Q 2,103,776

UNITED STATES PATENT OFFICE- '-NOVEL GLUE PRODUCT FOR GLUING VENEERS ANDonoss-PLY SHEETS Edouard Geistlich, Wolhusen, Switzerland No Drawing.Original application December24, 1934, Serial No. 759,085. Divided andthis application November 18, 1936, Serial No. 111,555 In GermanyOctober 28, 1933 7 Claims. (01. 134-233) This application is a divisionof my application ample urea or thio-urea or derivates thereof, and forUnited States patent filed December 24th, aldehydes, particularlyformaldehyde or poly- 1934, Serial No. 759,085, and has for its objectmerides thereof such as paraformaldehyde, the a novel glue product forgluing veneers and crossrelation of glue to urea varying between 3:1 to

5 ply sheets of wood. I 6:1 and the relation of carbamide to aldehyde 5It is known to utilize for gluing wood solutions between 3:1 to 2:1. inwater of mixtures of animal adhesives, i. e. This novel product has theremarkable quality gluten containing adhesives, such as bone, skin ofbinding under the influence of pressure and or leather glues, with urea,thio-urea or derivates heat which hitherto was unheard of 'for gluten ofthe latter substances. containing adhesives. 10 Glues of this kind have,however, the draw- Alternatively, the animal glue can be partly backs ofbinding too slowly during applying heat replaced by filling materials,for example up to to the glue joints and of being too little resistivean amount of 60%. against. the influence of moisture. The considerabletechnical advance thus ob- It has also already been proposed to use as'tained by means of the invention consists in the adhesives compositionsof casein, urea, formalnovel glue product providing after itsdissolution dehyde and water. Such adhesives are, however, in water. atroom temperature or when slightly not applicable. for gluing wood, theirusefulness heated (40 C.) and its application to the joinbeingrestricted to the production of, surface ing surface for a glued jointto ensue which is coats and plastic masses. fast to the influence ofmoisture andis distin- 20 It is further known to render materials ofguishcd by the fact that even if the joining presglue-like nature orgelatine water soluble again sure is exerted at a temperature of 90 C.and by means of solutions of urea after these matemore and fine veneersfor example of oak or nut rials have become insoluble by effect offormalwood of minimum thickness are glued on,- no glue dehyde. I canpenetrate through the pores of the veneer 25 Thus by treating glues thathad been tanned to form pools on the upper side thereof. by means offormaldehyde or else gelatines with In consequence of the high initialstrength of urea it is, admittedly, possible to partly recover the workblanks held together by means of the the starting materials, for examplefrom spent novel adhesive which strength accrues from the rollerlaggings, but this regenerating operation simultaneous presence of urea,thio-turea or der- 30 results, due to deterioration of the agglomeratedivates of these substances, and formaldehyde, gluten molecules in such aconsiderable reduction viz. polymerides o-r derivates thereof, ifdesired of quality that the adhesive product obtained in in combinationwith filling materials, acids, acid this way is no longer applicable forgluing wood. or acid giving 011 salts, the glued together pieces F t erms regenerated g e cks the can be removed from the heated press afterhav- 35 quality to bind under the influence of presing been acted upon.in the latter for a few sure and heat since for a modifiedregeneratminutes and without being cooled off, so that ing operation ithas been proposed to admix the considerable savings of time and heatingsteam urea to gluten containing substances prior to apare obtained. Inthis way is rendered possible 40 plying formaldehyde thereto with a viewto afto utilize animal glues instead of casein glues 40 fecting theapplicability of the glue within wide I and artificial resin glues,which 'was hitherto limits of temperature or in other words toprounknown.

vide for maintaining the adhesive product in In distinction from thealready proposed gluing liquid state for a relatively long time also atmethods in which foils are employed, the adraised temperature. vantageobtained by means of the invention con- 45 Moreover, adhesives havehitherto been used sists in the fact, that the temperatures andpreswhich consist of condensation products of an sures required forcarrying out the gluing are' early stage of urea-formaldehyde, ifdesired in much lower and that the novel method is reliable combinationwith a slight percentage amount -(at even under severe conditions inwhich gluing by I the most 10%) of glue. Adhesives of this sort, meansof foils fails. 1 do however, endure only for a limited length of time.The method according to the invention permits According to the presentinvention, the novel of adapting the qualification of the adhesive toproduct, which can be applied for gluing veneers the special purpose forwhich it is to be used in and cross-ply sheets of wood, is a watersoluble wide limits by varying the relation of the permixture of animalglue, carbamide, as for ex'- centage amounts of animal glue to urea,thio- 55 the one hand and for example formaldehyde in form of itspolymerides or derivates on the other hand (within the limits stated),if desired by:

Hereinafter two examples are given from which it will be evident inwhich manner the method according to the invention can be applied.

Example 1 10 kilograms of a mixture consisting of 78.0 percent by weightofpowdered bone glue (50 meshes per square centimeter), 14.0 percent byweight of urea, 7.0 percent by weight of paraformaldehyde and 1.0 byweight of liquid paraifin are admixed to 6 to 8 liters of water of 40"C. by stirring.

The viscous solution thus obtained is for example applied to both sidesof two veneers of alderwood of 1.5 millimeters thickness in thin coats,whereupon between the two alder-wood veneers an intervening ply ofalder-wood of 2 millimeters thickness is inserted and on top of eachalder-wood veneera strong okoum veneer of 1 millimeter thickness isplaced.

This sheet thus composed of five plies is then subjected during 12minutes to the action of a hydraulic heated press at a temperature of100 C. and a. pressure of 6 to 8 kilograms per square centimeter. Onopening the press a five cross-ply sheet definitely glued is obtainedwithout prior cooling.

If it is desired to produce a three cross-ply sheet 10 minutes pressingsumces under similar working conditions.

- Example 10 kilograms of a mixture consisting of 27.8 percent by weightof powdered bone glue (50 meshes per square centimeter), 23.0 percent byweight of urea, 9.0 percent by weight of paraformaldehyde, 37.0 percentby weight of heavy spar'or prepared chalk, 0.2 percent by weight ofoxalic or lactic acid and 3.0 percent by weight of liquid paraflln aredissolved in 4 to 6 liters of water of room temperature.

The viscous solution thus obtained is for example applied to the woodensheet carrier in a thin coat and then slightly allowed to dry, where-,

upon on the plating with fine veneers for examurea or'derivates of thelatter substances on ple of nut or oak-wood of 0.4to 0.6 millimeterthickness, the assembly is inserted in the heated press. The pressingoperation is effected preferably at a temperature of 90 C. and apressure of from 3.5 to 5 kilograms per square centimeter. After ,10minutes duration the definitely veneer plated sheet is taken out of thepress without prior cooling.

Veneers and cross-ply sheets of wood produced as specified in the aboveexamples are devoid of of an animal glue material, carbamide, and alde-'hydes in a relation of said glue material to carbamide varying between3: 1 and 6: 1, and a relation of carbamide to aldehyde varying between3:1 and 2:1.

2. A glue product comprising a water solution of an animal gluematerial, urea, and aldehydes in a relation of said glue material tourea varying between 3:1 and 6:1, and a relation of urea to-aldehydevarying between 3:1 and 2:1.

3. A glue product comprising a water solution .of an animal gluematerial, thio-urea, and

aldehydes in a relation of said glue material to thio-urea varyingbetween 3:1 and 6:1, and a relation of thio-urea to aldehyde varyingbetween 3:1 and 2:1.

4. A glue product comprising a water-solution of an animal gluematerial, a derivate of a carbamide, and aldehyde in a relation of saidglue material to said derivate varying between 3:1 and 6:1, and arelation of said derivate to 'aldehyde varying between 3:1 and 2:1.

5 A glue product comprising a water solution of an animal glue material,carbamide and formaldehyde in a relation of said glue material tocarbamide varying between 3:1 and 6:1, and a relation of carbamide toformaldehyde varying between 3:1 and 2:1.

6. A glue product comprising a water solution of an animal gluematerial, carbamide, and a polymeride of formaldehyde in a relation ofglue material to carbamide varying between 3:1 and 6:1, and a relationof carbamide to said polymeride varying between 3:1 and 2:1.

7. A glue product comprising a water solution of a mixture of animalglue material and a EDOUAIiD GEISTLICH.

